Apparatus and method for removing moisture

ABSTRACT

The present invention relates to a moisture removal apparatus and method for accurately detecting moisture generation in an early stage and quickly removing it so as to prevent steam or frost from being formed on glass surfaces of vehicles and industrial devices, and other surfaces. The apparatus comprises a surface resistance detector ( 50 ) including two detection terminals attached on an insulation surface with a predetermined gap therebetween, and showing different resistances according to an amount of moisture on the insulation surface; a static electricity preventer ( 60 ) preventing static electricity generation to the signal sensed by the surface resistance detector ( 50 ); a moisture sensor ( 70 ) determining moisture states through variations of the current that flows according to resistances of the surface resistance detector ( 50 ), and outputting a corresponding signal; and a driver ( 80 ) being operable to the signal output by the moisture sensor ( 70 ) and removing moisture generated on the surface.

BACKGROUND OF THE INVENTION (a) Field of the Invention

[0001] The present invention relates to an apparatus and method forremoving moisture. More specifically, the present invention relates to amoisture removing apparatus and method for accurately and easilydetecting moisture generation in an early stage and quickly removing itso as to prevent steam or frost from being created on glass surfaces ofvehicles and industrial devices as well as other surfaces, and toprevent moisture such as rainwater from blocking a distance of vision.

(b) Description of the Related Art

[0002] As economies have developed and people have become more affluent,the number of cars has greatly increased, and they have now becomenecessities of life even though regarded as luxuries or exhibitions ofwealth in the past.

[0003] However, as car distribution has increased, car accidents havealso increased, and the people concerned and their families heavilysuffer from death or damage caused by the car accidents, which generatessocial problems.

[0004] Accordingly, many efforts have been made to prevent caraccidents, and techniques for preventing them and minimizing injuriesand loss of life from car accidents have been developed.

[0005] Research for enhancing the distance of vision during driving hasprogressed in the field for preventing car accidents, includingtechniques for removing moisture caused by steam, frost, and rainwater.

[0006] In the rainy summer time or during very cold winter, thetemperature difference between the interior and exterior of a car islarge, the humidity inside the car increases which frequently generatessteam on the windows, and this steam may obstruct a driver's view tothereby cause very dangerous driving situations.

[0007] When steam is generated on the windows, the driver conventionallycontrols the temperature in the car to reduce the humidity. In thewinter, moisture in the air inside the car is condensed on the windowsthat are cooled because of the cold external temperature to becomesteam, the driver starts a heating system such as a heater and anelectric heating apparatus such as heat wires to raise the temperatureof the windows, thereby preventing the moisture in the interior air frombeing condensed.

[0008] In the above-described prior art, the driver undertakes a properaction after seeing the steam form on the windows. That is, the driverperceives that the steam begins to be formed on the windows, directlystarts a heating apparatus, an electric heating apparatus, or a coolingsystem, and when a predetermined time has passed, the steam disappears.Therefore, since the driver's view is not clear for a long time, itproblematically requires a long time to achieve a safe distance of view.

[0009] In order to prevent the generation of condensed moisture, such assteam and frost, chemicals may be applied to the windows. Namely,chemicals for preventing steam generation are coated on the windows ormirrors so that the steam may not be formed when the temperature and thehumidity change. In this method, the chemicals may not be coateduniformly, they may partially peel off to cause a scattered reflection,and they may damage the windows as well as people.

[0010] To solve the problems and demerits, many types of apparatus forautomatically sensing the generation of moisture on a surface andremoving the moisture have been developed. FIG. 15 shows an exemplifiedapparatus.

[0011] As shown in FIG. 15, a prior art moisture remover comprises: amoisture sensor 10 for sensing generation of moisture on a window andoutputting corresponding electrical signals; a microcomputer 20 forreceiving the electrical signals from the moisture sensor 10,calculating them, and outputting a moisture removal signal when it isdetermined that the moisture is generated; and a driver 30 for removingsteam formed on the window in response to the moisture removal signalsoutput by the microcomputer 20.

[0012] The moisture sensor 10 comprises: a temperature sensor 11 forsensing the temperature inside a vehicle, and outputting correspondingelectric signals; a humidity sensor 12 for sensing the humidity thereinand outputting corresponding electric signals; and a CCD (charge coupleddevice) 13 for sensing the window and outputting corresponding electricsignals.

[0013] The driver 30 comprises: an electric heating apparatus 31 forusing power to generate heat and heating the windows in response to themoisture removal signal output by the microcomputer 20; and a coolingand heating apparatus 32 for supplying cold or hot air into the vehicleto control the temperature therein.

[0014] An operation of the prior art moisture remover will now bedescribed.

[0015] When the temperature sensor 11 senses the temperature in thevehicle and outputs an electric signal, and the humidity sensor 12senses the humidity therein and outputs an electric signal, themicrocomputer 20 detects a time when steam is formed on the windowsaccording to an input temperature value and an input humidity value, andit outputs a moisture removal signal when it is determined to be thetime at which the steam is formed.

[0016] When the moisture removal signal is output by the microcomputer20, the cooling and heating apparatus 32 or the electric heatingapparatus 31 is individually operated to remove the moisture formed onthe windows.

[0017] That is, as a heater or an air conditioner is driven as thecooling and heating apparatus 32, the temperature in the vehicle iscooled to prevent the moisture in the air inside the vehicle from beingcondensed in the summer, or the windows are heated to prevent themoisture in the air inside the vehicle from being condensed on thewindows in the winter.

[0018] Also, by driving the electric heating apparatus 31, the moisturecondensed on the windows is evaporated.

[0019] As described above, the prior art senses formation of steam orfrost on the vehicle windows in the initial stage and removes it,thereby providing a clear view to the driver.

[0020] In addition, a CCD camera 13 may be installed in the vehicle totake desired images, and the corresponding images are analyzed by themicrocomputer 20 to determine whether steam is formed to thereby outputa moisture removal signal.

[0021] In the moisture remover, the temperature sensor 11 and thehumidity sensor 12 are separately installed in the vehicle, valuessensed by the temperature sensor 11 and the humidity sensor 12 arecalculated by the microcomputer 20 to determine whether the steam isformed, but since the sensed values may vary depending on the locationsof the temperature sensor 11 and the humidity sensor 12, correspondingreliabilities of these determining references are reduced.

[0022] The moisture remover additionally uses an expensive microcomputer20 that executes much calculation, and accordingly, it problematicallyincreases the cost of production.

[0023] Further, when steam instantly occurs in the CCD camera 13, themoisture remover fails to accurately determine moisture occurrence, andit requires a complex circuit and signal calculation for imageprocessing, thereby increasing the cost of production.

[0024] Ultrasonic waves or infrared rays may be used to sense generationof moisture such as formation of steam or frost, which also requires asystem for processing the ultrasonic waves and the infrared rays, andwhich requires complex calculation by the microcomputer usingcorresponding values, and hence, the whole system becomes complicated,the production cost becomes high, and it requires too much time todetermine the generation of steam.

SUMMARY OF THE INVENTION

[0025] It is an object of the present invention to provide an apparatusand method for easily and accurately sensing moisture formation andremoving the same so as to prevent moisture generation including steamor frost formation in vehicles or in industrial fields.

[0026] In one aspect of the present invention, an apparatus for removingmoisture formed on a surface comprises: a surface resistance detectorfor detecting resistance of the surface, and outputting a correspondingsignal; a moisture sensor for determining moisture generation statesthrough variation of a current that flows according to the resistance ofthe surface resistance detector, and outputting a moisture sensingsignal; and a driver for being operable according to the moisturesensing signal output by the moisture sensor to remove moisturegenerated on the surface.

[0027] If the target surface to be sensed is an insulator, the surfaceresistance detector comprises: a first terminal of conductive material,being attached on the surface, and being coupled to the moisture sensor;and a second terminal of conductive material, being attached on thesurface at a predetermined distance from the first terminal, andreceiving power.

[0028] The surface resistance detector further comprises a groundsubstrate, attached on the bottom of the target surface to be sensed,for preventing generation of electromagnetic interference or staticelectricity on the target surface.

[0029] If the target surface to be sensed is conductive, the surfaceresistance detector comprises: an insulation substrate with a highhydrophilic property, being attached on the surface; a first terminal ofconductive material, being attached on the insulation substrate, andbeing coupled to the moisture sensor; and a second terminal ofconductive material, being attached on the insulation substrate at apredetermined distance from the first terminal, and receiving power.

[0030] The surface resistance detector further comprises a groundsubstrate formed between the insulation substrate, the first terminal,and the second terminal.

[0031] The surface resistance detector uses heat wires provided on glasswindow surfaces of a vehicle.

[0032] In another aspect of the present invention, an apparatus forremoving moisture generated on a surface comprises: a surface resistancedetector for detecting resistance of the surface, and outputting acorresponding signal; a moisture sensor for determining moisturegeneration states through variations of the current that flows accordingto resistance of the surface resistance detector, and outputting acorresponding moisture sensing signal; a controller for receiving themoisture sensing signal from the moisture sensor, and controlling toremove moisture generated on the surface; and a driver being operableaccording to a control signal output by the controller, for removing themoisture generated on the surface.

[0033] The moisture sensor comprises: a reference current generator forgenerating a reference current for determining moisture sensing states,and outputting the reference current; a current detector for determiningmoisture states through variations of the current that flows accordingto resistance of the surface resistance detector, and outputting acorresponding signal; a detection signal output unit for outputtingcorresponding logical value signals according to detected values outputby the current detector; a signal smoother for converting the logicalvalue signals output by the detection signal output unit into smootheddigital signals, and outputting the digital signals; and a currentsource supply for supplying current used for an operation of the currentdetector and the detection signal output unit.

[0034] The moisture sensor comprises: a voltage source for generating apredetermined voltage; a reference resistor for using the voltage of thevoltage source, generating a reference current used for determiningmoisture sensing states, and outputting the reference current; and anoperational amplifier for receiving variations of the current that flowsaccording to the resistance of the surface resistance detector,comparing them with the reference current input through the referenceresistor, determining moisture states, and outputting a correspondingsignal.

[0035] The moisture sensor comprises: a first resistor for receivingdriving power, and supplying power used for an operation of the surfaceresistance detector; a second resistor for converting the signal outputby the surface resistance detector into a voltage signal, and outputtingthe voltage signal; and an operational amplifier for receiving a signal(input through the second resistor) of the surface resistance detectorthrough a non-inverting terminal, smoothing the signal, and outputtingthe smoothed signal to the driver.

[0036] The controller comprises: an analog-digital converter forconverting the current sensed by the moisture sensor into a digitalsignal, and outputting it; a microcomputer for receiving the moisturesensing signal output by the moisture sensor, determining moisturegeneration states, generating a corresponding moisture removal controlsignal, outputting the same to the driver, receiving the digital signaloutput by the analog-digital converter, and providing information ongeneration and amount of moisture to a user; and a display fordisplaying the signals output by the microcomputer to the user.

[0037] In still another aspect of the present invention, a method for toremoving moisture by using a signal output by a moisture sensor forsensing moisture generation states through variations of the currentthat flows according to resistance of a surface comprises: (a) reading amoisture sensing signal output by the moisture sensor for apredetermined time frame to determine whether the moisture generation isinstantaneous or continuous; (b) controlling to remove the generatedmoisture when the moisture is continuously generated in (a); (c) readingthe moisture sensing signal output by the moisture sensor for apredetermined time after the control of (b) to determine whether themoisture is completely removed; and (d) terminating moisture removalcontrol when it is determined in (c) that the moisture is completelyremoved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings, which are incorporated in andconstitute a part of the specification, illustrate an embodiment of theinvention, and, together with the description, serve to explain theprinciples of the invention:

[0039]FIG. 1 shows a moisture remover according to a first preferredembodiment of the present invention;

[0040]FIG. 2 shows an exemplified installation of the moisture removeraccording to a first preferred embodiment of the present invention;

[0041]FIG. 3 shows a steam formation phenomenon;

[0042]FIG. 4 shows a moisture remover according to a second preferredembodiment of the present invention;

[0043]FIG. 5 shows a moisture remover according to a third preferredembodiment of the present invention;

[0044]FIG. 6 shows a moisture remover according to a fourth preferredembodiment of the present invention;

[0045]FIG. 7 shows a moisture remover according to a fifth preferredembodiment of the present invention;.

[0046]FIG. 8 shows a flowchart for a moisture removal method accordingto the preferred embodiment of the present invention;

[0047]FIG. 9 shows a surface resistance detector when a sensing targetsurface is an insulator in FIG. 1;

[0048]FIG. 10 shows a surface resistance detector for preventingelectromagnetic interference (EMI) and electrostatic phenomena in FIG.1;

[0049]FIG. 11 shows a surface resistance detector when a sensing targetsurface is a conductor in FIG. 1;

[0050]FIG. 12 shows formation of steam generated between each terminal;

[0051]FIG. 13 shows surface tension and a contact angle;

[0052]FIG. 14 shows contact angles of droplets of water; and

[0053]FIG. 15 shows a prior art moisture remover:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] In the following detailed description, only the preferredembodiment of the invention has been shown and described, simply by wayof illustration of the best mode contemplated by the inventor(s) ofcarrying out the invention. As will be realized, the invention iscapable of modification in various obvious respects, all withoutdeparting from the invention. Accordingly, the drawings and descriptionare to be regarded as illustrative in nature, and not restrictive.

[0055]FIG. 1 shows a moisture remover according to a first preferredembodiment of the present invention.

[0056] As shown, the moisture remover comprises: a surface resistancedetector 50; a static electricity preventer 60; a moisture sensor 70;and a driver 80.

[0057] The surface resistance detector 50 comprises two metallicterminals attached on a window surface with a predetermined gaptherebetween, and it detects resistance that follows moisture formationsuch as steam or frost generation. The static electricity preventer 60prevents generation of static electricity that can affect signals sensedby the surface resistance detector 50.

[0058] The moisture sensor 70 determines moisture states through avariation of the current that flows according to the resistance of thesurface resistance detector 50, and outputs a corresponding signal. Thedriver 80 removes the moisture formed on the glass surface in responseto the signal output by the moisture sensor 70.

[0059] The moisture sensor 70 comprises a current detector 71 fordetecting the variation of the current that flows to the surfaceresistance detector 50, and for outputting a corresponding detectionsignal; and a signal smoother 75 for converting a value of the detectionsignal output by the current detector 71 into a smoothed driving signal,and outputting it.

[0060] In this instance, the current detector 71 comprises pnptransistors Q71 and Q72, and npn transistors Q73 and Q74. The base ofthe transistor Q71 is coupled to a metallic film of the surfaceresistance detector 50 or one of detection terminals of conductive tape,and the collector of the transistor Q71 is grounded. The base of thetransistor Q72 is coupled to the emitter of the transistor Q71, and thecollector of the transistor Q72 is coupled to the base of the transistorQ73. The emitters of the transistors Q73 and Q74 are grounded, and thecollector of the transistor Q73 is coupled to the base of the transistorQ74. Driving power Vcc is supplied to the emitter of the transistor Q72and the collector of the transistor Q73, and the collector of thetransistor Q74 is coupled to the signal smoother 75.

[0061] The signal smoother 75 comprises a resistor R75, a capacitor C75,and a light emitting diode (LED) L75. The resistor R75 is coupled to thecapacitor C75 in series between the driving power Vcc and the ground,and the coupling point of the resistor R75 and the capacitor C75 iscoupled to an output terminal of the current detector 71 and the driver80. The LED L75 is coupled between the coupling point and the ground.

[0062] The static electricity preventer 60 comprises diodes D61 and D62coupled in series between the driving power Vcc and the ground in thecounter direction, and the coupling points of the diodes D61 and D62 arecoupled to the surface resistance detector 50.

[0063] Referring to FIGS. 1 through 3, an operation of the moistureremover according to the first preferred embodiment of the presentinvention will be described.

[0064]FIG. 2 shows an exemplified installation of the moisture removeraccording to the first preferred embodiment of the present invention,and FIG. 3 shows a steam formation phenomenon.

[0065] As shown in FIG. 2, a metallic film of the surface resistancedetector 50 coated in metal or a detection terminal of conductive tapeis attached on a portion of the window 90 where steam is formed.

[0066] When moisture is formed (e.g., steam is formed on the windowglass 90) while one of the detection terminals is coupled to the staticelectricity preventer 60, and the other of the detection terminals isgrounded, the resistance between the detection terminals is reduced suchthat the current flows between the detection terminals.

[0067] The steam is provided on the window glass because the moisture inthe air in the vehicle reaches the dew point and the moisture is formedas droplets of water on the cold window glass, which reduces theresistance.

[0068] In this instance, if polyethylene for preventing staticelectricity is used as the detection terminals, it is very effective fordetecting the current. That is, general polyethylene is not conductive,but polyethylene for preventing static electricity is processed with asmall quantity of metallic film and it accordingly has weak conductivitywith a high resistance of several tens of giga-ohms. When the moistureoccurs because of steam or frost, the resistance changes.

[0069] Namely, the polyethylene for preventing static electricity has ahigh intrinsic resistance and it flows no current under normalconditions, but when in the steam is generated, the resistance isreduced such that a minute current may flow because of the moisture.

[0070] In general, since the window glass is coated with a predeterminedfilm, the resistance changes slightly when the steam is formed on it,differing from ordinary glass plates, and accordingly, the metal-coatedpolyethylene for preventing static electricity may be used for thedetection terminals in the surface resistance detector 50. Thepolyethylene for preventing static electricity is very thin as vinyl andis easily adhered to the glass, it is semitransparent so as not toobstruct the driver's view, and it maintains the temperature of thecontact surface to instantly form the steam on the window glass when themoisture is formed on the window glass, so it has a fast response speed.

[0071]FIG. 3 shows a glass surface with moisture thereon in the form ofsteam or frost. In the case of general glass material, H₂o molecules arecondensed on the surface of the window glass to reduce the resistancethat is proportional to its length.

[0072] However, in the case of an insulator that has undergone surfaceprocessing and has limitless surface resistance as does window glass, ahigh resistive material such as metal-coated polyethylene is attached toit, as shown in FIG. 3, to thereby reduce the resistance and allowdetection of the current that passes as a result of the moisture.

[0073] As to its operation, with reference to FIG. 1, when steam orfrost is formed, or rain or snow falls to generate moisture, theresistance between the detection terminals of the surface resistancedetector 50 is reduced to allow the flow of current, and when thecurrent reaches the bias current of the transistor Q71 of the currentdetector 71, the transistor Q71 is turned on, and the transistor Q72 isthen turned on.

[0074] When the transistor Q72 is turned on, the current flows to thebase of the transistor Q72 to turn on the transistor Q73, andaccordingly, no current flows to the base of the transistor Q74.

[0075] Hence, the transistor Q74 is turned off, and the steam formationdetermining signal Vo output to the driver 80 becomes a high drivingsignal to drive the driver 80.

[0076] The driver 80 includes electric heating devices such as windowheat wires installed in conventional vehicles, and cooling and heatingsystems such as heaters and air conditioners.

[0077] In the normal condition when no steam is formed, since theresistance between the two detection terminals of the surface resistancedetector 50 allows no current to flow, the transistor Q71 of the currentdetector 71 is turned off, and the transistor Q72 is accordinglymaintained in an off state.

[0078] Since the transistor Q73 is also turned off to supply the drivingpower Vcc to the base of the transistor Q74, the transistor Q74 isturned on to output a low steam formation determining signal, and thedriver 80 is not driven.

[0079] The static electricity preventer 60 controls such that a signalfrom static electricity may not be input to the signal input of themoisture sensor 70. The signal smoother 75 of the moisture sensor 70converts the signal output by the current detector 71 into a smoothedsignal for driving the driver 80, and outputs the same.

[0080] Therefore, when no steam occurs, the transistor Q74 is not turnedon and the driver 80 is not driven, but when the steam is formed on thewindow glass, the resistance between the two detection terminals of thesurface resistance detector 50 changes, the transistors Q71, Q72, andQ73 are turned on to turn off the transistor Q74, and accordingly, thedriving power Vcc is supplied to the driver 80 to prevent steamformation.

[0081] In the first preferred embodiment of the present invention, pnptransistors are used for the transistors Q71 and Q72, and npntransistors for the transistors Q73 and Q74, and other types oftransistors may also be used without being limited to these.

[0082] The sensors of the surface resistance detector 50, in order todetect moisture, are required to not absorb moisture, to showtemperatures (e.g., a surface temperature) to be detected under a suddentemperature change condition, and to not become warm.

[0083] In the first preferred embodiment of the present invention,metal-coated polyethylene for preventing static electricity is applied,and the polyethylene has a resistance of between 1 and 999 giga-ohms inthe normal condition. Further, other high resistance materials may beused instead of the polyethylene.

[0084] Methods for installing the surface resistance detector 50 arevaried according to states of a sensing target surface as shown in FIGS.9 through 11.

[0085] When the sensing target surface is an insulator, as shown in FIG.9, a conductive metallic film or a terminal 52 of conductive tape isattached to a sensing surface 51 of the insulator to be coupled to thestatic electricity preventer 60, and a terminal 53 is attached at apredetermined distance from the terminal 52 to supply power Vin+.

[0086] In order to prevent generation of electromagnetic interference(EMI) or static electricity on the sensing target surface, a groundsubstrate 54 is additionally provided under the sensing surface 51, asshown in FIG. 10.

[0087] To remove steam formation from the conductive surface and notfrom the window glass or general glass, it is required to insert aninsulator between the metallic film or the conductive tape and theconductive surface such that the metallic film or the conductive tape isnot directly adhered to the corresponding conductive surface.

[0088] If the insulator is not inserted therebetween, the currentcontinues to flow when the steam is either formed or not according tothe conductive surface, thereby failing to perform accurate sensing.

[0089] That is, when the sensing target surface is conductive, as shownin FIG. 11, an insulated sensing surface 51 is set, terminals 52 and 53are attached on it, a ground substrate 54 is attached under the sensingsurface, and an insulation substrate 55 is additionally attached underthat so all of them are attached to the target surface.

[0090] In this instance, when a material with a hydrophilic property isused for the sensing surface 51, its detecting sensitivity may beenhanced.

[0091] That is, in the case of a material that has a contact angle ofalmost 0 degrees which is generated when the moisture touches thematerial, the material has excellent wetness and detection performance,and it is more suitable if the material has a contact angle of within 0to 90 degrees, and when a material with an ultra-hydrophilic propertyhaving a contact angle of from 0 to 15 degrees is used, betterperformance is achieved.

[0092] Referring to FIG. 11, when the static electricity or EMI is notgreat, the ground substrate 54 may be omitted, which is not illustrated.

[0093] In the case of applying the two terminals of the surfaceresistance detector 50, components in the conventional vehicle may beused without additional components.

[0094] Namely, in the case of conventional vehicles, heat wires areprovided on the rear window to remove steam or to melt snow to obtain aclear view, and two of the heat wires may be used as two terminals torealize the surface resistance detector 50.

[0095] In particular, when heat wires for removing the frozen snow onthe windshield are provided around wipers in the case of expensivevehicles, if the corresponding heat wires are used as two terminals ofthe surface resistance detector 50, better performance may be obtainedwithout additional devices.

[0096] In the first preferred embodiment of the present invention,removal of moisture according to formation of steam on the windows isdescribed, and the present invention may further be applied to variousindustrial fields that have safety problems as a result of formation ofmoisture and that require removal and prevention of moisture where itmay form.

[0097] Also, in the first preferred embodiment of the present invention,since the windows are insulators, formation of steam is detected using ametallic film or a conductive tape, and in the case of general glasssubstrates used for general industrial fields, the glass surfaces areused as sensors without using additional detection terminals forpreventing static electricity.

[0098] That is, when a detection electrode is directly attached on theglass substrate, and another electrode is grounded on a portion at apredetermined distance from the detection electrode, no current flowsbecause of intrinsic resistance of the glass. When steam is formed, theresistance is reduced because of the moisture, and the current flows sothe formation of steam may be detected, and hence the surface mayfunction as a sensor.

[0099] In addition, other materials of high resistance may also be usedfor the glass surface.

[0100]FIGS. 12 through 14 show a method for sensing moisture on asurface, and referring to them, a condition of the surface resistancedetector 50 for sensing moisture will be described.

[0101] As shown in FIG. 12, when moisture is formed on an insulatedsurface, minute droplets of water are formed, and a barrier level (i.e.,resistance) of electron flow is determined according to patterns of thedroplets of water.

[0102] That is, the barrier level of the electron flow is determineddepending on the surface tension of the insulator and the condenseddroplets of water, and in this instance, detecting performance isdetermined with respect to the contact angle that represents patterns ofdroplets of water.

[0103] In other words, in the case conductive liquid droplets such assteam are formed, electrons fluidly flow to the terminals when thedroplets are connected.

[0104] When a liquid droplet falls on a surface of a solid material, aforce applied to a predetermined point X is determined by a surfacetension γs of a solid material, a surface tension γ₁ of a liquidmaterial, and an interfacial tension γs₁ between a liquid material and asolid material, and their relationship is expressed in Equation 1.

γs= cos θ+γs ₁   Equation 1

[0105] where the angle θ represents the contact angle for indicatingwetness of the surface of a solid material. FIG. 13 shows a relationshipbetween the surface tension and the contact angle.

[0106] The contact angle shows an angle generated when liquid isthermodynamically equivalent on the surface of solid material, and it isdetermined by adhered droplets of water. A low contact angle indicates ahigh wetness (i.e., a hydrophilic property) and a high surface energy,and a high contact angle represents a low wetness (i.e., a hydrophobicproperty) and a low surface energy. FIG. 14 shows the representativepatterns of droplets of water for various contact angles.

[0107] In general, the surface tension of water varies according totemperature, from 60 to 76 dyne/cm, it is greatest next to mercury (Hg),and it forms a drop pattern for minimizing a surface area.

[0108] As the contact angle becomes greater, the gaps between thedroplets of water function as resistance material that interferes withcurrent flow, and hence it is difficult to initially detect moisture,and as the contact angle becomes lower, it is easier to detect moisture.It is desirable for the contact angles to have values of less than 90degrees regarding its wetness environment so that detection performancemay be adequate.

[0109] Further, in the case the sensing target surface has a wateroutlet effect, that is, in the case the contact angle is greater than 90degrees, which interferes with electron flow, if a new surface tensionγ₁ ^(′) of a liquid and an interfacial tension γs₁ ^(′) between a liquidand a solid are lowered by adding a surfactant, the contact angle may bereduced as expressed in Equation 2.

γs>γ₁ ^(′) cos θ+γs ₁ ^(′)  Equation 2

[0110] In this case, since the surface tension n is greater than the sumof the surface tension γ₁ ^(′) of the liquid and the interfacial tensionγs₁ ^(′) between the liquid and the solid, the droplets of water spreadat the point X in the direction of the surface tension γs of the solidto thereby reduce the contact angle.

[0111] Therefore, in order to enhance detecting performance of thesurface resistance detector 50, a surfactant is provided on the sensingsurface, the sensing surface is coated with a material with a highhydrophilic property or the terminals are formed on a substance with ahigh hydrophilic property.

[0112]FIG. 4 shows a moisture remover with increased precision ofmoisture detection and enhanced smoothness compared to the firstpreferred embodiment of the present invention.

[0113] With reference to drawings, the moisture remover according to asecond preferred embodiment of the present invention will now bedescribed.

[0114] As shown in FIG. 4, the moisture remover comprises a surfaceresistance detector 100, a static electricity preventer 200, a moisturesensor 300, a controller 400, and a driver 500.

[0115] The surface resistance detector 100 may be realized in variousways as described in the first preferred embodiment of the presentinvention, and no repeated description will be provided.

[0116] The static electricity preventer 200 comprises diodes D210 andD220 and a capacitor S210, and it prevents static electricity generationto the signals sensed by the surface resistance detector 100.

[0117] The moisture sensor 300 comprises a current source supply 310, areference current generator 320, a current detector 330, a detectionsignal output unit 340, and a signal smoother 350, and it determinesmoisture states through variations of the current that flows accordingto the resistance of the surface resistance detector 100, and outputscorresponding signals.

[0118] The current source supply 310 comprises current sources 11, 12,13, and 14, and it supplies the current required for operating thecurrent detector 330 and the detection signal output unit 340.

[0119] The reference current generator 320 comprises a voltage sourceVin- and a resistor R320, and it supplies the reference current used fordetermining whether moisture is sensed.

[0120] The current detector 330 comprises pnp transistors Q331, Q332,Q333, and Q334, and npn transistors Q335 and Q336, and it detectsvariations of the current that flows to the surface resistance detector100, compares them with the voltage generated by the reference currentgenerator 320, and outputs corresponding detection signals to thedetection signal output unit 340.

[0121] In this instance, the base of the transistor Q331 is coupled to adetection terminal of the surface resistance detector 100, the collectorof the transistor Q331 is grounded, and the current source 11 of thecurrent source supply 310 is supplied to the emitter of the transistorQ331. The base of the transistor Q332 is coupled to the emitter of thetransistor Q331, the collector of the transistor S332 is coupled to thedetection signal output unit 340, and the current source 12 of thecurrent source supply 310 is supplied to the emitter of the transistorQ332.

[0122] The base of the transistor Q333 is coupled to the emitter of thetransistor Q334, and the current source 12 of the current source supply310 is supplied to the emitter of the transistor Q333. The collector ofthe transistor Q334 is grounded, and the current source 13 and theoutput signal of the reference current generator 320 are respectivelysupplied to the emitter and the base of the transistor Q334. Thecollector of the transistor Q335 is coupled to the collector of thetransistor Q332, the base of the transistor Q335 is coupled to thecollector of the transistor Q333, and the emitter of the transistor Q335is grounded. The collector and the base of the transistor Q336 arecoupled, and the emitter of the transistor Q336 is grounded.

[0123] The detection signal output unit 340 comprises: a transistor Q341having a base receiving output signals of the current detector 330, acollector receiving the current source 14 of the current source supply310, and a is grounded emitter; and a transistor Q342 having a basecoupled to the collector of the transistor Q341, and a grounded emitter,and it outputs corresponding signals according to detected values outputby the current detector 330. The transistors Q341 and Q342 include npntransistors.

[0124] The signal smoother 350 comprises a resistor R350 and a capacitorC350 coupled in series between the driving power Vcc and the ground, andthe coupling point of the resistor R350 and the capacitor C350 iscoupled to an output terminal of the detection signal output unit 340.The signal smoother 350 converts values of detection signals output bythe detection signal output unit 340 into driving signals, and outputsthem.

[0125] The controller 400 comprises an analog-digital (A/D) converter410, a microcomputer 420, and a display 430, and the controller 400receives signals from the moisture sensor 300, controls to removemoisture, and notifies a user of moisture generation.

[0126] An operation of the moisture remover according to the secondpreferred embodiment of the present invention will be described below.

[0127] When moisture including steam is generated, resistance betweentwo terminals of the surface resistance detector 100 is reduced to flowthe current, the current is supplied to the base of the transistor Q331,and when this current is greater than the current supplied to thetransistor Q334 through the resistor R320 of the reference currentgenerator 320, the transistors Q332 and Q335 are turned on.

[0128] Accordingly, the transistor Q341 of the detection signal outputunit 340 is turned on, the transistor Q342 is turned off, and the valueof the driving power Vcc supplied to the signal smoother 350 is outputto the controller 400 through the resistor R350 to thereby notify, usinga logical high value, that moisture is generated on the sensing surface.

[0129] However, when no moisture is generated or when the currentflowing between the two terminals of the surface resistance detector 100is less than the current supplied to the transistor Q334 through theresistor R320 of the reference current generator 320, the transistorQ332 is turned off, the transistor Q335 is then tuned off, and thetransistors Q333 and Q334 are turned on.

[0130] Accordingly, the transistor Q341 of the detection signal outputunit 340 is turned off, the transistor Q342 is turned on, the drivingpower Vcc is supplied to the signal smoother 350 through the eighthtransistor Q342, and a logical low value is provided to the controller400 to thereby notify that no moisture is generated on the sensingsurface.

[0131] The controller 400 drives the driver 500 or stops the sameaccording to values of the signal output by the moisture sensor 300thereby controlling to remove the moisture.

[0132] Referring to FIG. 8, an operation of the controller 400 will bedescribed in detail.

[0133] The microcomputer 420 of the controller 400 reads a moisturesensing signal output by the moisture sensor 300 in step S10 todetermine whether moisture is formed in step S20.

[0134] When it is determined that moisture is formed, the microcomputer420 allows a predetermined time frame to be passed, and reads a moisturesensing signal again in step S30 to determine whether moisturegeneration is maintained in step S40.

[0135] When it is determined that the moisture generation is maintainedafter the predetermined time frame, the microcomputer 420 controls thedriver 500 to remove moisture in step S60.

[0136] The microcomputer 420 then reads a moisture sensing signal againin step S70 to determine whether the moisture is removed in step S80.

[0137] When it is determined that the moisture is removed, themicrocomputer 420 allows a predetermined time frame to be passed, andreads a signal output by the moisture sensor 300 again to determinewhether the moisture removal is finished temporarily or completely instep S100.

[0138] When it is determined that the moisture is completely removed,the microcomputer 420 controls the driver 500 to terminate moistureremoval driving in step S110.

[0139] As controlled above, an operation of moisture sensing or moistureremoval is accurately controlled when an instantaneous error isgenerated.

[0140] When it is found that moisture is generated in the previous stepS40, the microcomputer 420 controls the A/D converter 410 to convert thecurrent detected by the moisture sensor 300 into digital values,displays the digital values on the display 430 so that the user may viewthem, and calculates an expected removal time and notifies the user ofthe time to thereby provide convenience to the user.

[0141] In a like manner of the first preferred embodiment of the presentinvention, the driver 500 uses an electrical heating system such as heatwires installed on the conventional vehicular windows, and cooling andheating devices such as heaters and air conditioners.

[0142] As operated above, the moisture is accurately sensed, andinformation on the generated moisture and time required for removing themoisture is provided to the user, thereby enhancing satisfaction causedby moisture removal.

[0143] An operational amplifier may be substituted for the moisturesensor 300, which will be described with reference to FIG. 5.

[0144]FIG. 5 shows a moisture remover according to a third preferredembodiment of the present invention.

[0145] As shown, the moisture remover comprises a surface resistancedetector 100, a static electricity preventer 200, a moisture sensor 600,a controller 400, and a driver 500.

[0146] The surface resistance detector 100, the static electricitypreventer 200, the controller 400, and the driver 500 may be realized invarious ways as described in the second preferred embodiment of thepresent invention, and no repeated description will be provided.

[0147] The moisture sensor 600 comprises a reference voltage sourceVin-, a reference resistor R610, and an operational amplifier OP610.

[0148] An operation of the moisture remover according to the thirdpreferred embodiment 6f the present invention will now be described.

[0149] The operational amplifier OP610 of the moisture sensor 600receives the current from the surface resistance detector 100 through anon-inverting input terminal, compares it with the reference currentlin-input through an is inverting input terminal, and outputs acorresponding signal to the controller 400.

[0150] That is, when moisture is formed on the surface, and the currentoutput by the surface resistance detector 100 is greater than thereference current lin-, the operational amplifier OP610 outputs alogical high signal to the controller 400 so that the controller 400 maycontrol to remove moisture.

[0151] When the moisture formed on the surface is removed, and thecurrent output by the surface resistance detector 100 is less than thereference current lin-, the operational amplifier OP610 outputs alogical low signal to the controller 400 so that the controller 400 mayterminate controlling of moisture removal.

[0152] As described above, by using the operational amplifier OP610 toconfigure the moisture sensor 600, the moisture removal may beaccurately controlled.

[0153]FIG. 6 shows a circuit for detecting moisture that is more stablethan the third preferred embodiment of the present invention.

[0154] Referring to FIG. 6, a moisture remover according to a fourthpreferred embodiment of the present invention will be described.

[0155] The configuration of the fourth preferred embodiment is similarto that of the third preferred embodiment except that the moisturesensor of the fourth embodiment comprises resistors R710 and R720 anduses the operational amplifier OP710 as a voltage follower so as toobtain more accurate values output from the surface resistance detector100.

[0156] Namely, more accurate values of the current input through thesurface resistance detector 100 may be obtained by use of the resistorsR710 and R720, and in particular, the resistor R720 functions as a pulldown resistor.

[0157] The operational amplifier OP710 smoothes the signals inputthrough a non-inverting terminal, and outputs them to directly drive thedriver.

[0158] In the following, no descriptions of the components also includedin the third embodiment will be provided.

[0159] In the case of a different polarity of the bias voltage than inthe fourth preferred embodiment, resistors R810 and R820 are provided asshown in FIG. 7, and hence, flexible processing may be possibleaccording to polarities of the signals used by the operational amplifierOP810. FIG. 7 shows this fifth preferred embodiment of the presentinvention.

[0160] That is, in the fifth preferred embodiment of the presentinvention, differing from the fourth preferred embodiment, one terminalof the resistor R810 is coupled to an input terminal of the surfaceresistance detector 100 and another terminal of the resistor R810 isgrounded, and one terminal of the resistor R820 is coupled to anon-inverting terminal of the operational amplifier OP810 and anotherterminal of the resistor R820 is coupled to the driving power Vcc,thereby functioning as a pull up resistor.

[0161] Since the current direction according to the fifth embodiment isopposite to that of the fourth embodiment, no descriptions will beprovided so as to prevent repetition.

[0162] Resistors (not illustrated) may also be used to accurately obtainsignals of the surface resistance detector in FIG. 1 or 4, which may befully realized by persons skilled in the art.

[0163] In each embodiment, bipolar transistors are used for the moisturesensors 70 and 300 to realize a desired circuit, and in addition, MOStransistors or MOS-FET transistors may also be used instead of thebipolar transistors, which is obvious to persons skilled in the art.

[0164] Therefore, the present invention immediately determines moistureformation when moisture (or steam) is formed on the windows of avehicle, and it automatically removes moisture and prevents the same,thereby providing clear and safe driving views.

[0165] Further, the present invention prevents accidents that may becaused by obstruction of the driver's vision because of moisturegenerated through steam formation, and frost, rain or snow.

[0166] In addition, since the present invention that operates in theabove-described manner accurately removes moisture through a simpleconfiguration, it saves production costs.

[0167] While this invention has been described in connection with whatis presently considered to be the most practical and preferredembodiment, it is to be understood that the invention is not limited tothe disclosed embodiments, but, on the contrary, is intended to covervarious modifications and equivalent arrangements included within thespirit and scope of the appended claims.

What is claimed is:
 1. An apparatus for removing moisture formed on asurface, comprising: a surface resistance detector for detectingresistance of the surface, and outputting a corresponding signal; amoisture sensor for determining moisture generation states throughvariation of a current that flows according to the resistance of thesurface resistance detector, and outputting a moisture sensing signal;and a driver for being operable according to the moisture sensing signaloutput by the moisture sensor to remove moisture generated on thesurface.
 2. The apparatus of claim 1, wherein when the target surface tobe sensed is an insulator, the surface resistance detector comprises: afirst terminal of conductive material, being attached on the surface,and being coupled to the moisture sensor; and a second terminal ofconductive material, being attached on the surface at a predetermineddistance from the first terminal, and receiving power.
 3. The apparatusof claim 2, wherein the surface resistance detector further comprises aground substrate, attached on the bottom of the target surface to besensed, for preventing generation of electromagnetic interference orstatic electricity on the target surface.
 4. The apparatus of claim 1,wherein when the target surface to be sensed is an insulator, thesurface resistance detector comprises: an insulation substrate with ahigh hydrophilic property, being attached on the surface; a firstterminal of conductive material, being attached on the insulationsubstrate, and being coupled to the moisture sensor; and a secondterminal of conductive material, being attached on the insulationsubstrate at a predetermined distance from the first terminal, andreceiving power.
 5. The apparatus of claim 4, wherein the material witha high hydrophilic property has a contact angle, formed when themoisture is contacted to the material, ranging from 0 to 90 degrees. 6.The apparatus of claim 4, wherein the material with a high hydrophilicproperty has a contact angle, formed when the moisture is contacted tothe material, ranging from 0 to 15 degrees.
 7. The apparatus of claim 1,wherein when the target surface to be sensed is conductive, the surfaceresistance detector comprises: an insulation substrate with a highhydrophilic property, being attached on the surface; a first terminal ofconductive material, being attached on the insulation substrate, andbeing coupled to the moisture sensor; and a second terminal ofconductive material, being attached on the insulation substrate at apredetermined distance from the first terminal, and receiving power. 8.The apparatus of claim 7, wherein the surface resistance detectorfurther comprises a ground substrate formed between the insulationsubstrate, the first terminal, and the second terminal.
 9. The apparatusof claim 1, wherein when the surface is a material that has a surfaceresistance of from 1 to 999 giga-ohms, the surface resistance detectoruses the surface as a detector without using an additional highresistive material.
 10. The apparatus of claim 1, wherein the surfaceresistance detector uses heat wires provided on a window glass surfaceof a vehicle.
 11. The apparatus of claim 1, wherein the steam formationdetermination unit comprises: a current detector for detectingvariations of the current that flows according to variations of theresistance of the surface resistance detector, and for outputting acorresponding detecting signal; and a signal smoother for converting avalue of the detecting signal output by the current detector into astable driving signal, and outputting the same.
 12. The apparatus ofclaim 11, wherein the current detector comprises: a first transistorbeing turned on when the current increases to greater than apredetermined value according to variations of the resistance of thesurface resistance detector; a second transistor being turned on whenthe first transistor is turned on; a third transistor being turned onwhen the second transistor is turned on; and a fourth transistor beingturned off when the third transistor is turned on, and outputting acurrent detecting signal.
 13. The apparatus of claim 11 wherein thesignal smoother comprises: a resistor having one terminal coupled todriving power, and another terminal coupled to an output terminal of thecurrent detector; and a capacitor having one terminal coupled to anotherterminal of the resistor, and another terminal being grounded.
 14. Theapparatus of claim 1, further comprising a static electricity preventerfor preventing generation of static electricity to signals sensed by thesurface resistance detector.
 15. The apparatus of claim 14, wherein thestatic electricity preventer comprises: a first diode having a cathodecoupled to driving power, and an anode coupled to one terminal of thesurface resistance detector; and a second diode having a cathode coupledto one terminal of the surface resistance detector, and an anode beinggrounded.
 16. An apparatus for removing moisture generated on a surface,comprising: a surface resistance detector for detecting resistance ofthe surface, and outputting a corresponding signal; a moisture sensorfor determining moisture generation states through variations of acurrent that flows according to resistance of the surface resistancedetector, and outputting a corresponding moisture sensing signal; acontroller for receiving the moisture sensing signal from the moisturesensor, and controlling to remove moisture generated on the surface; anda driver being operable according to a control signal output by thecontroller, for removing the moisture generated on the surface.
 17. Theapparatus of claim 16, wherein the moisture sensor comprises: areference current generator for generating a reference current fordetermining moisture sensing states, and outputting the referencecurrent; a current detector for determining moisture states throughvariations of the current that flows according to resistance of thesurface resistance detector, and outputting a corresponding signal; adetection signal output unit for outputting corresponding logical valuesignals according to detected values output by the current detector; asignal smoother for converting the logical value signals output by thedetection signal output unit into smoothed digital signals, andoutputting the digital signals; and a current source supply forsupplying a current source used for an operation of the current detectorand the detection signal output unit.
 18. The apparatus of claim 17,wherein the current source supply comprises: first through third currentsources for supplying power used for an operation of the currentdetector; and a fourth current source for supplying a current used foroperation of the detection signal output unit.
 19. The apparatus ofclaim 17, wherein the reference current generator comprises: a voltagesource for generating a predetermined voltage; and a resistor forallowing the current according to the resistance to flow.
 20. Theapparatus of claim 17, wherein the current detector comprises: a firsttransistor having a base coupled to a detection terminal of the surfaceresistance detector, a collector being grounded, and an emitterreceiving the first current source of the current source supply; asecond transistor having a base coupled to the emitter of the firsttransistor, an emitter receiving the second current source of thecurrent source supply, and a collector coupled to the detection signaloutput unit; a third transistor having an emitter receiving the thirdcurrent source of the current source supply, a base receiving an outputsignal of the reference current generator, and a collector beinggrounded; a fourth transistor having a base coupled to the emitter ofthe third transistor, and an emitter receiving the second current sourceof the current source supply; a fifth transistor having a collectorcoupled to the collector of the second transistor, a base coupled to thecollector of the fourth transistor, and an emitter being grounded; and asixth transistor having a base and a collector coupled to the collectorof the fourth transistor, and an emitter being grounded.
 21. Theapparatus of claim 17, wherein the detection signal output unitcomprises: a seventh transistor having a base receiving an output signalof the current detector, a collector receiving the fourth current sourceof the current source supply, and an emitter being grounded; and aneighth transistor having a base coupled to the collector of the seventhtransistor, and an emitter being grounded.
 22. The apparatus of claim17, wherein the signal smoother comprises: a resistor having oneterminal coupled to driving power, and another terminal coupled to anoutput signal of the detection signal output unit; and a capacitorhaving one terminal coupled to another terminal of the resistor, andanother terminal being grounded.
 23. The apparatus of claim 16, whereinthe controller comprises: an analog-digital converter for converting thecurrent sensed by the moisture sensor into a digital signal, andoutputting it; a microcomputer for receiving the moisture sensing signaloutput by the moisture sensor, determining moisture generation states,generating a corresponding moisture removal control signal, outputtingthe same to the driver, receiving the digital signal output by theanalog-digital converter, and providing information on generation andamount of the moisture to a user; and a display for displaying thesignals output by the microcomputer to the user.
 24. The apparatus ofclaim 16, wherein the moisture sensor comprises: a voltage source forgenerating a predetermined voltage; a reference resistor for using thevoltage of the voltage source, generating a reference current used fordetermining moisture sensing states, and outputting the referencecurrent; and an operational amplifier for receiving variations of thecurrent that flows according to the resistance of the surface resistancedetector, comparing them with the reference current input through thereference resistor, determining moisture states, and outputting acorresponding signal.
 25. The apparatus of claim 16, wherein themoisture sensor comprises: a first resistor for receiving driving power,and supplying power used for an operation of the surface resistancedetector; a second resistor for converting the signal output by thesurface resistance detector into a voltage signal, and outputting thevoltage signal; and an operational amplifier for receiving a signal(input through the second resistor) of the surface resistance detectorthrough a non-inverting terminal, smoothing the signal, and outputtingthe smoothed signal to the driver.
 26. A method for removing moisture byusing a signal output by a moisture sensor for sensing moisturegeneration states through variations of the current that flows accordingto resistance of a surface, comprising: (a) reading a moisture sensingsignal output by the moisture sensor for a predetermined time frame todetermine whether the moisture generation is instantaneous orcontinuous; (b) controlling to remove the generated moisture when themoisture is continuously generated in (a); (c) reading the moisturesensing signal output by the moisture sensor for a predetermined timeafter the control of (b) to determine whether the moisture is completelyremoved; and (d) terminating moisture removal control when it isdetermined in (c) that the moisture is completely removed.
 27. Themethod of claim 26, further comprising: calculating a moisture amountgenerated on the surface, and displaying its value after the control in(b).